Brief overview of Unix and Linux commands

Below is a listing of each of the Unix and Linux commands currently listed on Computer Hope and a brief explanation of what each of the commands do. This is a full listing which means not all the below commands will work with your distribution and may also not work because of your privileges. Clicking on any of the commands will display additional help and information about that command.

Command Description
a2p Creates a Perl script from an awk script.
ac Prints statistics about user connection time.
access A system function which checks real user's permissions to access a file.
addgroup Adds a new group to the system.
adduser Adds a new user to the system.
agrep Version of the grep utility which also matches approximate patterns.
alias Creates another name for a command or command string.
apropos Searches the manual pages for a keyword or regular expression.
apt-cache Queries the APT software package cache.
apt-get Command line tool for working with APT software packages.
aptitude Text-based front-end for the APT package management system.
ar Creates, modifies, and extracts from archives.
arch Displays the architecture of the current host.
arp Manipulate the system ARP cache.
as An assembler.
aspell Interactive spell checker.
at Command scheduler.
awk Awk script processing program.
basename Deletes any specified prefix from a string.
bash Command Bourne interpreter
bc Calculator.
bdiff Compare large files.
bfs Editor for large files.
bg Continues a program running in the background.
biff Enable and disable incoming mail notifications.
break Break out of while, for, foreach, or until loop.
bs Battleship game.
bye Alias often used for the exit command.
cal Calendar.
calendar Display appointments and reminders.
cancel Cancels a print job.
cat View or modify a file.
cc C compiler.
cd Change directory.
cfdisk A more user-friendly version of the fdisk disk partitioning utility.
chdir Change directory.
checkeq Language processors to assist in describing equations.
checknr Check nroff and troff files for any errors.
chfn Modify your own information or if superuser or root modify another users information.
chgrp Change a groups access to a file or directory.
chkey Change the secure RPC key pair.
chmod Change the permission of a file.
chown Change the ownership of a file.
chroot Run a command or shell from another directory, and treats that directory as root.
chsh Change login shell.
cksum Display and calculate a CRC for files.
clear Clears screen.
cmp Compare files.
col Reverse line-feeds filter.
comm Compare files and select or reject lines that are common.
compress Compress files on a computer.
continue Break out of while, for, foreach, or until loop.
cp Copy files.
cpio Creates archived CPIO files.
crontab Create and list files that you want to run on a regular schedule.
crypt Function used to encrypt passwords.
csh Execute the C shell command interpreter
csplit Split files based on context.
ctags Create a tag file for use with ex and vi.
cu Calls or connects to another Unix system, terminal or non-Unix system.
curl Transfer a URL.
cut Cut out selected fields of each line of a file.
date Tells you the date and time in Unix.
dc An arbitrary precision arithmetic package.
dd Convert and copy a file.
delgroup Remove a group from the system.
deluser Remove a user from the system.
depmod Generates a list of kernel module dependences, modules.dep, and associated map files.
deroff Removes nroff/troff, tbl, and eqn constructs.
df Display the available disk space for each mount.
dhclient Dynamic Host Configuration Protocol Client.
diff Displays two files and prints the lines that are different.
dig DNS lookup utility.
dircmp Lists the different files when comparing directories.
dirname Deliver portions of path names.
dmesg Print or control the kernel ring buffer.
dos2unix Converts text files between DOS and Unix formats.
dpkg Queries, installs, removes, and maintains Debian software packages and their dependencies.
dpost Translates files created by troff into PostScript.
du Tells you how much space a file occupies.
echo Displays text after echo to the terminal.
ed Line oriented file editor.
edit Text editor.
egrep Search a file for a pattern using full regular expressions.
eject Ejects removable media.
elm Program command used to send and receive e-mail.
emacs Text editor.
enable Enables and disables LP printers.
env Displays environment variables.
eqn Language processors to assist in describing equations.
ex Line-editor mode of the vi text editor.
exit Exit from a program, shell or log you out of a Unix network.
expand Expand copies of files.
expr Evaluate arguments as an expression.
fc Lists, edits, or re-executes commands previously entered.
fdisk A disk partioning utility.
fg Continues a stopped job by running it in the foreground
fgrep Search a file for a fixed-character string.
file Tells you if the object you are looking at is a file or a directory.
find Finds files within a directory hierarchy.
findsmb List info about machines that respond to SMB name queries on a subnet.
finger Lists information about the user.
fmt Simple text formatters.
fold Filter for folding lines.
for Shell built-in functions to repeatedly execute action(s) for a selected number of times.
foreach Shell built-in functions to repeatedly execute action(s) for a selected number of times.
free  Display amount of free and used memory in the system
fsck Check and repair a Linux file system.
ftp Enables ftp access to another terminal.
fuser Identify processes using files or sockets.
gawk Powerful pattern-matching and processing language.
getfacl Display discretionary file information.
gethostname System call to get the hostname of the current processor.
gpasswd Administer /etc/group and /etc/gshadow.
gprof The gprof utility produces an execution profile of a program.
grep Finds text within a file.
groupadd Creates a new group account.
groupdel Enables a superuser or root to remove a group.
groupmod Enables a superuser or root to modify a group.
gunzip Expand compressed files.
gview A programmer's text editor.
gvim A programmer's text editor.
gzip Compress files.
halt Stop the computer.
hash Remove internal hash tables.
hashstat Evaluates the effectiveness of internal hash tables.
head Displays the first ten lines of a file, unless otherwise stated.
help Displays help for built-in shell commands.
history Display the command history.
host DNS lookup utility.
hostid Prints the numeric identifier for the current host.
hostname Set or print name of current host system.
id Shows you the numeric user and group ID on BSD.
ifconfig Sets up network interfaces.
ifdown Take a network interface down.
ifup Bring a network interface up.
info Read Info documents.
init Process control initialization.
iostat Reports Central Processing Unit (CPU) statistics and input/output statistics for devices and partitions.
ip Show and manipulate routing, devices, policy routing and tunnels.
isalist Display the native instruction sets executable on this platform.
iwconfig Configure a wireless network interface.
jobs List the jobs currently running in the background.
join Joins command forms together.
keylogin Decrypt the user's secret key.
kill Cancels a job.
killall Kills processes by name.
ksh Korn shell command interpreter.
last Displays a listing of the most recently logged-in users.
ld Link-editor for object files.
ldd List dynamic dependencies of executable files or shared objects.
less Opposite of the more command.
lex Generate programs for lexical tasks.
link Calls the link function to create a link to a file.
ln Creates a link to a file.
lo Allows you to exit from a program, shell or log you out of a Unix network.
locate List files in databases that match a pattern.
login Signs into a new system.
logname Returns users login name.
logout Logs out of a system.
losetup Sets up and controls loop devices.
lp Prints a file on System V systems.
lpadmin Configure the LP print service.
lpc Line printer control program.
lpq Lists the status of all the available printers.
lpr Submits print requests.
lprm Removes print requests from the print queue.
lpstat Lists status of the LP print services.
ls Lists the contents of a directory.
lsof Lists open files.
lzcat View compressed .lzma files.
lzma Compress files to .lzma file.
mach Display the processor of the current host.
mail One of the ways that allows you to read/send E-Mail.
mailcompat Provide SunOS 4.x compatibility for the Solaris mailbox format.
mailx Mail interactive message processing system.
make Executes a list of shell commands associated with each target.
man Display the documentation (manual page) of a given command.
merge Performs a merge of the contents of three files.
mesg Control if non-root users can send text messages to you.
mii-tool View, manipulate media-independent interface status.
mkdir Create a directory.
mkfs Build a Linux file system, usually a hard disk partition.
mkswap Sets up a Linux swap area.
modprobe Adds and removes modules from the linux kernel.
more Displays text one screen at a time.
mount Creates a file systems and remote resources.
mt Magnetic tape control.
mv Renames a file or moves it from one directory to another directory.
myisamchk Checks, repairs, optimises, or fetches information about a MySQL database.
mysql An open-source relational database management system.
mysqldump A tool for backing up or transferring mysql databases.
nc TCP/IP swiss army knife.
neqn Language processors to assist in describing equations.
netstat Shows network status.
newalias Install new elm aliases for user or system.
newform Change the format of a text file.
newgrp Log into a new group.
nice Invokes a command with an altered scheduling priority.
niscat Display NIS+ tables and objects.
nischmod Change access rights on a NIS+ object.
nischown Change the owner of a NIS+ object on a system running Solaris.
nischttl Change the time to live value of a NIS+ object.
nisdefaults Display NIS+ default values.
nisgrep Utilities for searching NIS+ tables.
nismatch Utilities for searching NIS+ tables.
nispasswd Change NIS+ password information.
nistbladm NIS+ table administration command.
nl Numbers the lines in a file.
nmap Network exploration tool and security port scanner.
nohup Runs a command even if the session is disconnected or the user logs out.
nroff Formats documents for display or line-printer.
nslookup Queries a name server for a host or domain lookup.
od Dump files in octal and other formats.
on Execute a command on a remote system, but with the local environment.
onintr Shell built-in functions to respond to (hardware) signals.
optisa Determine which variant instruction set is optimal to use.
pack Shrinks file into a compressed file.
pagesize Display the size of a page of memory in bytes, as returned by getpagesize.
parted A disk partition manipulation program.
partprobe Informs the operating system about changes to the partition table.
passwd Allows you to change your password.
paste Merge corresponding or subsequent lines of files.
pax Read/write and writes lists of the members of archive files and copy directory hierarchies.
pcat Compresses file.
perl Perl is a programming language optimized for scanning arbitrary text files, extracting information from those text files.
pg Files perusal filters for CRTs.
pgrep Examine the active processes on the system and reports the process IDs of the processes
pico Simple and very easy to use text editor in the style of the Pine Composer.
pine Command line program for Internet News and Email.
ping Sends ICMP ECHO_REQUEST packets to network hosts.
pkill Examine the active processes on the system and reports the process IDs of the processes
poweroff Stop the computer.
pr Formats a file to make it look better when printed.
priocntrl Displays or sets scheduling parameters of processes.
printenv Prints all or part of environment.
printf Write formatted output.
ps Reports the process status.
pstree Displays processes in tree format.
pvs Display the internal version information of dynamic objects within an ELF file.
pwd Print the current working directory.
quit Allows you to exit from a program, shell or log you out of a Unix network.
rcp Copies files from one computer to another computer.
readlink Prints the value of a symbolic link or canonical file name.
reboot Stop the computer.
red The "restricted" version of a line-oriented file editor.
rehash Recomputes the internal hash table of the contents of directories listed in the path.
rename Renames multiple files using a regular expression.
renice Alters the priority of running processes.
repeat Shell built-in functions to repeatedly execute action(s) for a selected number of times.
replace A string-replacement utility.
rgview A programmer's text editor.
rgvim A programmers text editor.
rlogin Establish a remote connection from your terminal to a remote machine.
rm Deletes a file without confirmation (by default).
rmdir Deletes a directory.
rn Reads newsgroups.
route Show and manipulate the IP routing table.
rpcinfo Report RPC information.
rsh Runs a command on another computer.
rsync Faster, flexible replacement for rcp.
rview A programmers text editor.
rvim A programmers text editor.
s2p Convert a sed script into a Perl script.
sag Graphically displays the system activity data stored in a binary data file by a previous sar run.
sar Displays the activity for the CPU.
scp Transfers files securely over a network connection.
screen Screen manager with VT100/ANSI terminal emulation.
script Records everything printed on your screen.
sdiff Compares two files, side-by-side.
sed Allows you to use pre-recorded commands to make changes to text.
sendmail Sends mail over the Internet.
service Runs a System V init script.
set Set the value of an environment variable.
setenv Set the value of an environment variable.
setfacl Modify the Access Control List (ACL) for a file or files.
sethostname System calls or set the hostname of the current processor.
sfdisk A low-level disk partitioning program.
sftp Secure file transfer program.
sh Runs or processes jobs through the Bourne shell.
shred Delete a file securely, first overwriting it to hide its contents.
shutdown Turn off the computer immediately or at a specified time.
sleep Waits a x amount of seconds.
slogin OpenSSH SSH client (remote login program).
smbclient An ftp-like client to access SMB/CIFS resources on servers.
sort Sorts the lines in a text file.
spell Looks through a text file and reports any words that it finds in the text file that are not in the dictionary.
split Split a file into pieces.
startx Starts an X Window System session.
stat Display file or filesystem status.
stop Control process execution.
strftime Formats strings that represent the system date and time.
strip Discard symbols from object files.
stty Sets options for your terminal.
su Become superuser or another user.
sudo Executes any command as the superuser.
swapoff Disables a Linux swap area.
swapon Enables a Linux swap area.
sysinfo Get and set system information strings.
sysklogd Linux system logging utilities.
tabs Set tabs on a terminal.
tail Delivers the last part of the file.
talk Talk with other logged in users.
tac Concatenate and print files in reverse.
tar Create tape archives and add or extract files.
tbl Preprocessor for formatting tables for nroff or troff.
tcopy Copy a magnetic tape.
tcpdump Dump traffic on a network.
tcsh A command-line shell similar to csh, with some additional features.
tee Read from an input and write to a standard output or file.
telinit Process control initialization.
telnet Uses the telnet protocol to connect to another remote computer.
test Check file types and compare values.
time Used to time a simple command.
timex The timex command times a command; reports process data and system activity.
todos Converts text files between DOS and Unix formats.
top Display Linux tasks.
touch Change file access and modification time.
tput Initialize a terminal or query terminfo database.
tr Translate characters.
traceroute Print the route packets take to network host.
trap A function which "traps" signals and interrupts, and reacts to them.
tree List the contents of a file hierarchy visually in a tree format.
troff Typeset or format documents.
tty Print the file name of the terminal connected to standard input.
ul Reads the named filenames or terminal and does underlining.
umask Get or set the file mode creation mask.
unalias Remove an alias.
unhash Remove internal hash table.
uname Print name of current system.
uncompress Uncompressed compressed files.
uniq Report or filter out repeated lines in a file.
unlink Call the unlink function to remove the specified file.
unlzma Decompress .lzma file.
unmount Disconnects a file systems and remote resources.
unpack Expands a compressed file.
until Execute a set of actions while/until conditions are evaluated TRUE.
unxz Decompress .xz files.
unzip List, test and extract compressed files in a ZIP archive.
uptime Display information about how long the system has been running.
useradd Create a new user or updates default new user information.
userdel Remove a users account.
usermod Modify a users account.
vacation Reply to mail automatically.
vgrind "Grind" nice program listings
vi Screen-oriented (visual) display editor based on ex.
vim A programmer's text editor.
view A programmer's text editor.
vipw A special command to safely edit password files.
visudo A special command to safely edit the "sudoers" file.
vmstat Reports statistics about virtual memory usage.
w Show who is logged on and what they are doing.
wait Await process completion.
wall Send a message to everybody's terminal.
wc Displays a count of lines, words, and characters in a file
wget Downloads files via HTTP or FTP, such as web pages.
whatis Displays short manual page descriptions.
whereis Locate a binary, source, and manual page files for a command.
while Repetitively execute a set of actions while/until conditions are evaluated TRUE.
which Locate a command.
who Displays who is on the system.
whoami Print effective userid.
whois Internet user name directory service.
write Send a message to another user.
X Execute the X Window System.
Xorg The executable of the X Window System server.
xargs Build and execute complex commands across multiple files.
xfd Display all the characters in an X font.
xhost Server access control program for X.
xinit The initializer of the X Window System.
xlsfonts Server font list displayer for X.
xset User preference utility for X.
xterm Terminal emulator for X.
xrdb X server resource database utility.
xz Compress files to .xz files.
xzcat View compressed .xz files.
yacc Short for yet another compiler-compiler, yacc is a compiler.
yes Repeatedly output a line with all specified STRING(s), or 'y'.
yppasswd Changes network password in the NIS database.
yum Interactive rpm based package manager.
zcat Compress files.
zip Compression and file packaging utility.
zipinfo Display technical information about a zip file.

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